---
typeId: req
recordId: benac-exec-008
fields:
  title: Interface invocation input
  statement: >-
    Invocation shall identify the requested package interface.

    Invocation shall identify descriptor snapshot CID or descriptor scope where
    descriptor configuration is relevant.

    Invocation shall identify request body, data class, caller principal where relevant,
    authentication context where relevant, and Local Policy context where relevant.

    If the caller requests a specific invocation contract snapshot, the Station shall
    attempt that contract or fail closed unless explicit recorded fallback policy
    authorizes another contract.

    If no invocation contract snapshot is requested, the Station shall derive the
    invocation contract from package declaration, selected package interface, descriptor
    scope, schema bindings, artifact availability, trust scope, capability grants,
    resource limits, Local Policy, operation status, and prior recorded attempts where
    relevant.

    The selected package interface, derived or requested invocation contract, and all
    blocked alternatives with reasons shall be recorded.

    The Station shall not silently fall back to another package interface or invocation
    contract unless Local Policy permits fallback and the invocation trace records it.

    The default fallback policy for requested package interfaces and requested
    invocation contracts shall be NoFallback.

    Inability to attempt an invocation contract shall be recorded as Station status and
    shall not by itself change package content validity.
  rationale: >-
    Packages can expose multiple schema-bound interfaces. Invocation selection must be
    interoperable, auditable, and policy-governed without classifying package internals.
  verification: >-
    A package with multiple interfaces records deterministic interface resolution. A
    requested missing interface, invalid request schema, invalid descriptor config,
    operation not currently mediated by the Station, and unavailable artifact each fail
    under default NoFallback policy. A separate test passes only when explicit fallback
    policy is present and the trace records fallback authority and reason.
  testable: true
  status: draft
  area: BENAC-EXEC
  sourceDocument: user-requested schema-first requirements cleanup
  sourceVersion: 2026-05-06
  sourceSections:
    - Package authoring
  order: 87.2
---
